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Where We Build
Underground bunkers and compounds, built for the ground they stand on.
Utah, Idaho, Montana and Wyoming are the four states rated Recommended on our HOLM map, and we also build in Colorado, Tennessee and Texas. Each asks different things of a structure below grade. These pages set out what we design for in each, with sources.
Recommended
Utah
Wasatch Fault design, collapsible soils, shallow groundwater and snow loads set by statute.
Read RecommendedIdaho
Basalt excavation on the Snake River Plain, central Idaho earthquakes and radon in two of five homes.
Read RecommendedMontana
Frost to four feet, snow loads to 140 psf, active seismic belts and radon in half of homes tested.
Read RecommendedWyoming
County-set codes, bentonite clay, the Teton fault and radon found in all 23 counties.
ReadAlso building in
Colorado
Expansive clay on the Front Range, a statewide wildfire code, frost to four feet and radon in every county.
Read Selective on the HOLM mapTexas
Shrink-swell clay, Hill Country limestone, flash floods, 137 tornadoes a year and radon in basements.
Read Strong on the HOLM mapTennessee
Karst and sinkholes, two seismic zones, tornado seasons in spring and fall, and radon in every county.
ReadWhat changes by state
Same standard,
different ground.
Every Styrkholm bunker meets the same published spec. What changes from state to state is the ground, the weather and the rules.
Rock and soil
Basalt in Idaho, bentonite in Wyoming and Colorado, limestone and karst in Texas and Tennessee. We test before we dig.
Frost, snow and storms
Frost from six inches in Texas to four feet in Montana, mountain snow loads to 140 psf, and tornado design in the South.
Earthquakes
The Wasatch Fault, central Idaho, southwest Montana, the Teton fault and Tennessee's two seismic zones. We engineer for them.
Radon
Found at the action level in every county of Wyoming, Colorado and Tennessee. Every bunker is mitigated and tested.
Codes and licensing
From one statewide code in Utah to county-by-county rules in Wyoming and Texas. We build to the residential code everywhere.
Water and septic
Water rights first, then a septic permit that works with fixtures below grade.
Tell us where you want to build.
We search for land, test the ground and design the whole compound. Consultations are private.